This invention relates to laser alignment devices.
Portable devices capable of indicating level, plumb and square alignment have been useful in the construction and carpentry trades for some time. The advent of laser technology has seen the use of portable laser emitting devices capable indicating level and plumb, as well as level, plumb and square alignments simultaneously. Such devices typically require some sort of tilt-compensation mechanism or self-leveling mechanism, to avoid the introduction of error when operated from a non-level surface. However, even with a tilt-compensation or self-leveling mechanism, such tools typically can only accurately indicate level and plumb within a range of inclinations of the tool relative to level. To avoid a user inadvertently relying on an erroneous indication of alignment, some tools provide an indication to the user, when the user is attempting to use the tool outside of a predefined range of inclinations, for example, by ceasing projection of alignment beams or causing the alignment beams to blink. Although level and plumb alignments may be inaccurate when the tool is inclined beyond a certain range, it may still be possible to achieve an accurate square alignment using the laser beams.
In some prior art tools, alignment is indicated with beams that form points of light or xe2x80x9cspotsxe2x80x9d on a surface against which they are projected. In some prior art tools, an invisible xe2x80x9clinexe2x80x9d can be imagined between two or more opposing and aligned spots to provide an alignment line. Other tools indicated alignment with beams that form the image of a straight line on the surface against which they are projected, that is, they project linear alignment beams.
The present invention provides apparatus and a method for projecting alignment lines. In general, in one aspect, the invention features an apparatus for projecting an indication of alignment, including a housing, a projection unit pendulously suspended in the housing to project output beams to indicate level, plumb and square and a damper to dampen pendular motion of the projection means. The apparatus further includes an error indicator to indicate when the housing is inclined such that the accuracy of the level and plumb directions are compromised, and an override to deactivate the error indicator, whereby the output beams can be used at least to indicate square.
Implementations of the invention may include one or more of the following. The projection unit can include at least one laser diode to emit a laser beam, a first and a second collimator to form a first and a second collimated beam, and a first and a second optical element to convert the first and second collimated beam into a first and a second linear output beam. The first and second linear output beams are projected from the housing in different but generally perpendicularly related directions, and can be used to indicate level, plumb and square alignment.
The error indicator can suspend projection of the output beams from the projection unit. The error indicator can indicate that the housing is inclined such that the accuracy of the level and plumb directions are compromised, when the housing is inclined in any direction in the range of approximately plus or minus 4 to 9 degrees from horizontal. In another implementation, the error indicator can indicate the housing is inclined such that the accuracy of the level and plumb directions are compromised, when the housing is inclined in any direction more than approximately 9 degrees from horizontal. The override can include digital circuitry to deactivate the error indicator in response to a user input.
Each collimator can include a focus lens, and in one embodiment each focus lens can be an aspheric lens. Each optical element can include a rod lens, or alternatively a cylinder lens. The damper can include a magnet mounted in the housing below the projection unit and a damping plate rigidly suspended from the projection unit, such that the damping plate is positioned above the magnet with a gap maintained therebetween sufficiently small that eddy currents are generated in the damping plate by motion thereof above the magnet. The apparatus can further include at least one battery to provide power to at least one laser diode of the projection unit.
A user interface configured to receive a user input can also be included in the apparatus. In response to a first user input, the projection unit can project a first output beam that can be used to indicate level. In response to a second user input, the projection unit can project a second output beam having a generally perpendicular relationship to the first output beam, whereby the second output beam can be used indicate plumb. In response to a third user input, the projection unit can project simultaneously the first and second output beams, whereby together the output beams can be used to indicate simultaneously level, plumb and square. In response to a fourth user input, the override can be employed to deactivate the error indicator, and the projection unit can project simultaneously the first and second output beams, whereby the output beams together can be used to at least indicate square.
In general, in another aspect, the invention features an apparatus for projecting an indication of alignment including a housing and a projection unit pendulously suspended in the housing to project linear output beams. The projection unit includes two laser diodes configured and arranged to emit two laser beams, two collimators configured and arranged to form the two laser beams into a first and second collimated beam, and an optical element configured and arranged to convert the first and second collimated beams into a first and a second linear output beam. The first and second linear output beams are projected from the housing in different but generally perpendicularly related directions, and can be used to simultaneously indicate level, plumb and square. The optical element includes a first and second lens to convert the first and second collimated beams into the first and second linear output beams, and a mount to mount the first and second lens to the projection unit.
For each lens, the mount includes a member in which the lens can be mounted and a base. The member also includes openings through which connectors can be positioned. The openings allow the member to be laterally displaced once the connectors are in position, to align the lens such that the linear output beam is symmetrically projected from the housing. The base is configured to attach to the member by the connectors. At least one connector includes a longitudinal adjustment mechanism to adjust the position of the lens such that the output beam is substantially straight. The base is mounted onto a support protruding from the projection unit and rotatable about the support to achieve true vertical in relation to the projection unit for the first lens and true horizontal in relation to the projection unit for the second lens.
The apparatus further includes a damper configured and arranged to dampen pendular motion of the projection unit.
Implementations of the invention may include one or more of the following. An error indicator can be configured and arranged to indicate when the housing is inclined such that the accuracy of the level and plumb directions are compromised. An override device can be configured and arranged to deactivate the error indicator, so that the output beams can be used as alignment lines to at least indicate square directions.
The error indicator can suspend projection of the linear output beams from the projection unit. The error indicator can indicate the housing is inclined such that the accuracy of the level and plumb directions are compromised, when the housing is inclined in any direction in the range of approximately plus or minus 4 to 9 degrees from horizontal. In another embodiment, the error indicator can indicate the housing is inclined such that the accuracy of the level and plumb directions are compromised, when the housing is inclined in any direction more than approximately 9 degrees from horizontal.
The longitudinal adjustment mechanism of the mount can be a spring. Each collimator can include a focus lens and, in one embodiment, each focus lens can be an aspheric lens. The first and second lens can each be a rod lens or a cylinder lens.
In general, in another aspect, the invention features a method for projecting an indication of alignment. The method includes forming a first alignment beam and a second alignment beam that is substantially perpendicular to the first alignment beam, whereby the first alignment beam indicates level, the second alignment beam indicates plumb, and the first and second alignment beams together indicate square. An error indicator is provided to indicate an error in the accuracy of the first and second alignment beams as indicators of level and plumb respectively. The error indicator can be deactivated, such that the first and second alignment beams together can be used at least to indicate square.
Implementations of the invention may include the following. The method can further include projecting a first and second laser beam, and collimating the first and second laser beam into a first and a second collimated beam incident on a first and a second optical element to convert the first and second collimated beams into the first and second alignment beams. The alignment beams can be projected in the image of substantially straight lines.
In general, in another aspect, the invention features a method of projecting indications of alignment from a laser-based tool, the method including, in response to a first user input received from a user interface that interacts with a user of the laser-based tool, projecting a first linear output beam that can be used to indicate level, and indicating any error in the accuracy of the first linear output beam as an indicator of level when the tool is positioned outside of a predetermined accuracy range.
In response to a second user input received from the user interface, a second linear output beam being substantially perpendicular to the first linear output beam is projected, whereby the second linear output beam can be used to indicate plumb. Any error in the accuracy of the second linear output beam as an indicator of plumb when the tool is positioned outside of the predetermined accuracy range is indicated.
In response to a third user input received from the user interface, the first and the second linear output beams are simultaneously projected that together can be used to indicate level, plumb and square alignment. Any error in the accuracy of the first and second linear output beams as indicators of level and plumb when the tool is positioned outside of the predetermined accuracy range is indicated.
In response to a fourth user input received from the user interface, the first and the second linear output beams are projected that together can be used at least to indicate square, even when the tool is positioned outside of the predetermined accuracy range.
Implementations of the invention may include one or more of the following. The tool is positioned outside the predetermined accuracy range when the tool is inclined in any direction in the range of approximately plus or minus 4 to 9 degrees from horizontal. In another embodiment, the tool is positioned outside the predetermined accuracy range when the tool is inclined in any direction more than approximately 9 degrees from horizontal.
The invention can be implemented to realize one or more of the following advantages. The laser alignment tool includes an error indicator permitting a user to operate the tool to accurately indicate level, plumb and square alignment, knowing the tool will be disabled, or the user will be otherwise notified, if the tool is positioned such that indications of level and plumb alignments may be inaccurate. A user has the option of deactivating the error indicator, to permit use of the tool to indicate square alignment when the tool is in virtually any position, including positions that would not accurately indicate level and plumb. The means for mounting the optical elements to the projection unit are configured to allow necessary adjustments to precisely position the optical elements to produce straight alignment lines with relative ease, while requiring a relatively small footprint. The small size of the mounting apparatus provides a compact and lightweight implementation of the tool, which a user can operate with one hand, leaving a free hand to make alignment marks.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features and advantages of the invention will be apparent from the description, the drawings, and the claims.